The invention relates to a corrugated or pleated flat material with a plurality of pleats or corrugations that run parallel to one another and successively define a pleat or corrugation peak and a pleat or corrugation valley, the peak and valley being connected to one another by way of a pleat or corrugation flank, wherein a fluid can flow through the flat material and the flat material has at least one deformable functional layer which rests on a supporting layer in the direction of throughflow of the fluid, said supporting layer comprising a supporting fabric, the functional layer allowing foreign substances to be removed from or delivered to the fluid.
By means of flat materials of this kind, a foreign substance, in particular a chemical, can be delivered to a fluid, for example a liquid, by means of desorption. For this purpose, the functional layer of the flat material may be impregnated with the chemical, the chemical being released when the fluid flows through. Flat materials of the kind mentioned at the beginning are also suitable for removing foreign substances or chemicals from the fluid flowing through, for example by adsorption, absorption or filtering. The functional layer can hold back foreign substances, for example contaminating particles, so that the content of foreign substances in the fluid can be reduced by virtue of the fluid flowing through the functional layer.
The through-flow of the fluid is accompanied by a loss of fluid pressure, i.e. the pressure of the fluid on the inflow side of the flat material is greater than on the outflow side, and the pressure loss causes mechanical loading of the functional layer. In order to avoid impairment of the functional layer, the latter is supported by means of a supporting layer, on which the functional layer rests. The supporting layer is of a grid-like configuration, for example in the form of a woven fabric.
In order to increase the effective surface area of the flat material, it is usually pleated or corrugated, since this allows the effectively usable surface area to be increased without the outer dimensions of the flat material having to be correspondingly increased. The loading of the flat material by the fluid flowing through may, however, have the consequence that the pleats or corrugations come to lie in close abutment against one another, in particular on the outflow side of the flat material. This increases the throughflow resistance of the flat material and consequently the pressure loss sustained by the fluid flowing through.
In the case of a flat material configured as a screen element, it is therefore proposed in U.S. Pat. No. 3,057,481 to make the supporting fabric as stiff and nondeformable as possible. For this purpose, the flat material is sintered, so that the functional layer is firmly bonded to the supporting layer. For this purpose, however, relatively thick filaments are required for the supporting layer, which is formed as a woven fabric, and this once again increases the pressure loss experienced by the fluid flowing through. Furthermore, in the case of flat materials of this kind, there is the risk of the materials suffering mechanical impairment, for example by formation of cracks, in particular under changing pressure loads. A further disadvantage is that, with a configuration of this kind, only sinterable functional layers can be used.
In DE 197 37 954 A1, to avoid what is known as pack forming, that is to say the pleats or corrugations of the flat material closely abutting one another, it is proposed to use an additional supporting structure with at least one supporting bead, which extends transversely in relation to the pleats, for example in the form of a helix. This is a relatively complex construction that entails not inconsiderable production costs.
It is an object of the present invention to develop a corrugated or pleated flat material of the kind mentioned at the beginning in such a way that it has greater mechanical load-bearing capacity and lower throughflow resistance.